115 lines
3.6 KiB
C++
115 lines
3.6 KiB
C++
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_RUNTIME_MEMORY_REGION_H_
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#define ART_RUNTIME_MEMORY_REGION_H_
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#include <stdint.h>
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#include "base/logging.h"
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#include "base/macros.h"
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#include "globals.h"
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namespace art {
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// Memory regions are useful for accessing memory with bounds check in
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// debug mode. They can be safely passed by value and do not assume ownership
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// of the region.
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class MemoryRegion {
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public:
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MemoryRegion() : pointer_(NULL), size_(0) {}
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MemoryRegion(void* pointer, uword size) : pointer_(pointer), size_(size) {}
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void* pointer() const { return pointer_; }
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size_t size() const { return size_; }
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size_t size_in_bits() const { return size_ * kBitsPerByte; }
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static size_t pointer_offset() {
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return OFFSETOF_MEMBER(MemoryRegion, pointer_);
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}
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byte* start() const { return reinterpret_cast<byte*>(pointer_); }
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byte* end() const { return start() + size_; }
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template<typename T> T Load(uintptr_t offset) const {
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return *ComputeInternalPointer<T>(offset);
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}
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template<typename T> void Store(uintptr_t offset, T value) const {
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*ComputeInternalPointer<T>(offset) = value;
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}
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template<typename T> T* PointerTo(uintptr_t offset) const {
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return ComputeInternalPointer<T>(offset);
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}
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// Load a single bit in the region. The bit at offset 0 is the least
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// significant bit in the first byte.
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bool LoadBit(uintptr_t bit_offset) const {
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uint8_t bit_mask;
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uint8_t byte = *ComputeBitPointer(bit_offset, &bit_mask);
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return byte & bit_mask;
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}
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void StoreBit(uintptr_t bit_offset, bool value) const {
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uint8_t bit_mask;
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uint8_t* byte = ComputeBitPointer(bit_offset, &bit_mask);
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if (value) {
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*byte |= bit_mask;
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} else {
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*byte &= ~bit_mask;
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}
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}
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void CopyFrom(size_t offset, const MemoryRegion& from) const;
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// Compute a sub memory region based on an existing one.
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MemoryRegion Subregion(uintptr_t offset, uintptr_t size) const {
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CHECK_GE(this->size(), size);
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CHECK_LE(offset, this->size() - size);
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return MemoryRegion(reinterpret_cast<void*>(start() + offset), size);
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}
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// Compute an extended memory region based on an existing one.
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void Extend(const MemoryRegion& region, uintptr_t extra) {
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pointer_ = region.pointer();
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size_ = (region.size() + extra);
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}
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private:
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template<typename T> T* ComputeInternalPointer(size_t offset) const {
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CHECK_GE(size(), sizeof(T));
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CHECK_LE(offset, size() - sizeof(T));
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return reinterpret_cast<T*>(start() + offset);
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}
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// Locate the bit with the given offset. Returns a pointer to the byte
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// containing the bit, and sets bit_mask to the bit within that byte.
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byte* ComputeBitPointer(uintptr_t bit_offset, byte* bit_mask) const {
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uintptr_t bit_remainder = (bit_offset & (kBitsPerByte - 1));
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*bit_mask = (1U << bit_remainder);
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uintptr_t byte_offset = (bit_offset >> kBitsPerByteLog2);
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return ComputeInternalPointer<byte>(byte_offset);
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}
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void* pointer_;
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size_t size_;
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};
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} // namespace art
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#endif // ART_RUNTIME_MEMORY_REGION_H_
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